This invention relates to a driving wheel slip control system for vehicles, and more particularly to an improvement in such a system, which enables to prevent stalling of an engine installed on the vehicle during deceleration thereof
A driving wheel slip control system for vehicles is known, e.g. from Japanese Provisional Patent Publication (Kokai) No. 48-18695, which is adapted to interrupt the fuel supply to the engine to inhibit combustion of the engine, when a predetermined slip state of the driving wheel(s) is detected, to thereby reduce the torque of the driving wheels and hence prevent excessive slip of the driving wheels.
However, this conventional driving wheel slip control system detects the predetermined slip state of the driving wheels based on the driving wheel speed or on the relationship between the driving wheel speed and the trailing wheel speed. Therefore, in the case that only the trailing wheels are in touch with the road surface but the driving wheels are out of touch therewith when the vehicle is running on a rough road, it can be misjudged during deceleration of the engine that the driving wheels are in the predetermined slip state, although the driving wheels actually are not in an excessive slip state, because on this occasion the driving wheel speed becomes higher than the trailing wheel speed since the driving wheels do not undergo a frictional force developed between the driving wheels and the road surface. The misjudgement causes a reduction in the torque of the driving wheels or the engine and hence degraded driveability and even engine stalling.